Content continues after advertisement

Differential Diagnosis: Hyponatremia

Marie A. Chartier, DVM, DACVIM, BluePearl Pet Hospital, Charlestown, Massachusetts

Internal Medicine

|September 2021|Peer Reviewed

Sign in to Print/View PDF

Differential Diagnosis: Hyponatremia

Following are differential diagnoses for patients presented with decreased blood sodium level.

Normal osmolality (290-310 mOsm/kg) 

  • Pseudohyponatremia (eg, hypertriglyceridemia, hyperproteinemia) 

Low osmolality (<290 mOsm/kg)

  • Polyuric renal failure
  • GI fluid loss (eg, vomiting, diarrhea, regurgitation, severe ileus with “pooled” insensible fluid losses) 
  • Hookworm infection
  • Severe dietary sodium restriction
  • Iatrogenic (eg, hypotonic fluids, diuretics)
  • Third-space loss 
    • Pancreatitis
    • Peritonitis
    • Pleural or peritoneal effusion
    • Uroabdomen
  • Hypoadrenocorticism
  • Edematous disorders 
    • Congestive heart failure
    • Liver failure
    • Nephrotic syndrome
  • Syndrome of inappropriate antidiuretic hormone secretion  
  • Psychogenic polydipsia

High osmolality (>310 mOsm/kg)

  • Diabetes mellitus (ie, secondary to hyperglycemia) 
  • Iatrogenic (ie, mannitol administration)


For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

All Clinician's Brief content is reviewed for accuracy at the time of publication. Previously published content may not reflect recent developments in research and practice.

Material from Clinician's Brief may not be reproduced, distributed, or used in whole or in part without prior permission of Educational Concepts, LLC. For questions or inquiries please contact us.


Clinician's Brief:
The Podcast

Listen as host Alyssa Watson, DVM, talks with the authors of your favorite Clinician’s Brief articles. Dig deeper and explore the conversations behind the content here.
Clinician's Brief provides relevant diagnostic and treatment information for small animal practitioners. It has been ranked the #1 most essential publication by small animal veterinarians for 9 years.*

*2007-2017 PERQ and Essential Media Studies

© Educational Concepts, L.L.C. dba Brief Media ™ All Rights Reserved. Privacy Policy (Updated 05/08/2018) Terms of Use (Updated 05/08/2018)